The invention relates to an X-ray tube which comprises a metal housing in which a rotary anode which is mounted on a shaft is rotatably journalled by means of two bearings, one bearing being connected on the one side to the metal housing and on the other side, by means of an electrical insulator, to the shaft, while the other bearing is connected on the one side to the shaft and on the other side, by means of an electrical insulator, to the housing.
An X-ray tube of this kind is disclosed in U.S. Pat. No. 4,024,424. Therein, bearings in the form of ball bearings are used. Only a comparatively small heat flow can be dissipated by way of these bearings. Therefore, the electrical power which can be applied to the anode disc, and hence the radiation power to be generated, is limited. Furthermore, the ball bearings must be situated at a comparatively large distance from the anode disc in order to prevent overheating during operation. Consequently, the length of such an X-ray tube in the direction of the drive shaft is comparatively large. Moreover, the loadability of the above X-ray tube is limited because increased loadability would necessitate a substantially increased diameter of the anode disc; this would mean a substantial increase of the moment of inertia and a substantially heavier drive motor would be required.